Differential energy costs of winter acclimatized common spiny mice Acomys cahirinus from two adjacent habitats

The common spiny mouse Acomys cahirinus, of Ethiopian origin, has a widespread distribution across arid, semi-arid and Mediterranean parts of the Arabian sub-region. We compared the daily energy expenditure (DEE), water turnover (WTO) and sustained metabolic scope (SusMS=DEE/resting metabolic rate) of two adjacent populations during the winter. Mice were captured from North- and South- facing slopes (NFS and SFS) of the same valley, comprising mesic and xeric habitats, respectively. Both DEE and SusMS winter values were greater in NFS than SFS mice and were significantly greater than values previously measured in the summer for these two populations in the same environments. However, WTO values were consistent with previously established values and were not significantly different from allometric predictions for desert eutherians. We suggest that physiological plasticity in energy expenditure, which exists both temporally and spatially, combined with stable WTO, perhaps reflecting a xeric ancestry, has enabled A. cahirinus to invade a wide range of habitats.     

Population genetic response to microsite ecological stress in wild barley, Hordeum spontaneum

Genetic diversity was studied in six subpopulations (a total of 60 individuals) of wild barley, Hordeum spontaneum , the progenitor of cultivated barley, sampled from six stations located along a transect of 300 m across the two opposing slopes of 'Evolution Canyon', a Mediterranean microsite at Lower Nahal Oren, Mt Carmel. The two opposing slopes are separated by between 100 and 400 m and designated SFS (South-Facing Slope) and NFS (North-Facing Slope) with each having three equidistant test stations. The SFS, which receives up to 300% more solar radiation, is drier, ecologically more heterogeneous, fluctuating, and more stressful than the NFS. Analysis of 12 RAPD primers, representing a total of 51 putative loci, revealed a significant inter- and intraslope variation in RAPD band polymorphism. A significantly higher proportion of polymorphic RAPD loci was found amongst the subpopulations on the SFS (mean P = 0.909) than on the NFS (mean P = 0.682), on the basis of the presence and absence of 22 strong bands. Polymorphism generally increased upwards from the bottom to the top of the SFS (0.636, 0.773, 0.955) and NFS (0.409, 0.500, 0.545), respectively. Gametic phase disequilibria estimates, D, revealed SFS and NFS unique predominant combinations which sharply differentiated the two slopes and indicated that there is differential interslope selection favouring slope-specific multilocus combinations of alleles, or blocks of genes over tens to hundreds of meters. This suggests that selection overrides migration. RAPD polymorphism appears to parallel allozyme diversity which is climatically adaptive and driven by natural selection in the same subpopulations at the microsite.     

Adaptive thermoregulation in golden spiny mice: the influence of season and food availability on body temperature

We studied the effect of food supplementation during summer and winter in seminatural field conditions on thermoregulation of a desert rodent, the golden spiny mouse Acomys russatus. We hypothesized that (a) under natural food availability (control conditions), mice will use less precise thermoregulation (i.e., an increase in the variance of body temperature [T(b)]) during winter because of low ambient temperatures (T(a)'s) and low food availability and during summer because of low food and water availability; (b) food supplementation will result in more precise thermoregulation during winter, but the effect will be smaller during summer because variation in T(b) in summer is also driven by water availability during that period. We found that under natural food availability, spiny mice thermoregulated more precisely during summer than during winter. They spent more time torpid during summer than during winter even when food was supplemented (although summer nights are shorter), allowing them to conserve water. Supplementing food resulted in more precise thermoregulation in both seasons, and mice spent less time torpid. In summer, thermoregulation at high T(a)'s was less precise, resulting in higher maximum T(b)'s in summer than in winter and when food was supplemented, in accord with the expected effect of water shortage on thermoregulation. Our results suggest that as expected, precise thermoregulation is beneficial when possible and is abandoned only when the costs of homeothermy outweigh the benefits.     

Do slope orientation and sampling location determine soil biota composition?

"Evolution Canyon" is a typical Mediterra-nean-basin canyon with a summer dry stream at the bottom and large differences in vegetation cover and solar radiation between the north-facing slope (NFS) and the south-facing slope (SFS). It is known to act as an abiotic mediator influencing the community structure of soil fauna. The aim of this study was to determine the spatial dispersion of soil microbial and free-living nematode communities in the open sites (between shrubs) in the upper (0-10 cm) soil layer at four altitudes on both slopes. The combination of relative soil moisture availability and temperature, known to be one of the main triggers for soil biota activity, was explained by slope orientation. The above-mentioned differences were found to significantly affect microbial biomass and CO2 evolution resulting in temporary stress, corresponding to higher values in metabolic quotient (qCO2) values. These differences may represent microbial investment in energy in order to overcome stress resulting from the microclimatic differ-ences between the two slopes. Moreover, the degree of substrate limitation (primary production due to the differences in plant cover) of microbial activity was explained by the difference in microbial functional groups. The total abundance of soil free-living nematodes was found to be 2-fold higher on the SFS than on the NFS. Thirty-nine genera, including 12 bacteria-feeders, 5 fungi-feeders, 12 plant-parasites, and 10 omnivore-predators, were found at the study site, with 34 genera on the NFS and 29 on the SFS. The generic diversity of the bacteria-feeding nematodes was higher on the SFS than on the NFS. This study elucidates the importance of slope orientation and its effect on the structural levels of soil microbial and nematode communities.     

Microsatellite analysis of Drosophila melanogaster populations along a microclimatic contrast at lower Nahel Oren canyon, Mount Carmel, Israel

Drosophila melanogaster populations collected at the south-facing slope (SFS) and north-facing slope (NFS) of lower Nahel Oren canyon, Mount Carmel, Israel display significant differences in survival and longevity at temperature, drought, and starvation stresses. Furthermore, significant assortative mating was previously observed between populations of the two slopes. We used a set of 48 microsatellite markers to analyze patterns of genetic differentiation between D. melanogaster populations from both slopes and D. simulans. Consistent with previous reports, we found D. simulans to be well differentiated from D. melanogaster. Genetic differentiation between SFS and NFS D. melanogaster populations was low (F(ST) = 0.0012). Also a tree of individuals based on the proportion of shared alleles and a model-based clustering method provided no evidence for population substructuring.     

Microclimate,developmental plasticity and community structure in artificial temporary pools

Solar radiation, which influences temperature and hydroperiod, should strongly influence colonization, development rate, development strategies and survival in temporary pools. We assessed these hypotheses at two spatial microscales with varying microclimate. One scale, ca. 200 m, was opposing slopes of a canyon on MT Carmel, Israel, referred to as 'Evolution Canyon' (Nevo, 1995). Due primarily to differential solar radiation, the warmer and drier South-facing slope (SFS) supports a savanna-like open park forest while the cooler, moister North-facing slope (NFS) is heavily forested, primarily with live oak. Using artificial pools, we assessed how these close but contrasting environments may influence developmental plasticity in the frog, Hyla savignyi, and colonization of insects. As expected, hydroperiod was considerably longer on the NFS. Hyla tadpole development was significantly faster on the SFS, while size at metamorphosis was greater on the NFS. Insect species richness was higher in NFS pools. The most common species, Culex pipiens, oviposited significantly more in NFS pools than in SFS pools. In the second scale, we placed pools only meters apart, but varying in shade and thus maximum temperature at Haifa University Campus, MT Carmel. Species richness and maximum temperature among pools were not correlated during winter and early spring (cool to mild temperatures), but were strongly and negatively correlated during early summer (hot temperatures). Thermal tolerance in the laboratory of selected species matched their thermal spatial distribution in the field. These results indicate that temperature can play a strong role in affecting developmental strategies, species′ distributions and community structure in temporary pools over a very small spatial scale. This revised version was published online in July 2006 with corrections to the Cover Date.     

Do slope orientation and sampling location determine soil biota composition?

“Evolution Canyon” is a typical Mediterranean-basin canyon with a summer dry stream at the bottom and large differences in vegetation cover and solar radiation between the north-facing slope (NFS) and the south-facing slope (SFS). It is known to act as an abiotic mediator influencing the community structure of soil fauna. The aim of this study was to determine the spatial dispersion of soil microbial and free-living nematode communities in the open sites (between shrubs) in the upper (0–10 cm) soil layer at four altitudes on both slopes. The combination of relative soil moisture availability and temperature, known to be one of the main triggers for soil biota activity, was explained by slope orientation. The above-mentioned differences were found to significantly affect microbial biomass and CO₂ evolution resulting in temporary stress, corresponding to higher values in metabolic quotient (qCO₂) values. These differences may represent microbial investment in energy in order to overcome stress resulting from the microclimatic differences between the two slopes. Moreover, the degree of substrate limitation (primary production due to the differences in plant cover) of microbial activity was explained by the difference in microbial functional groups. The total abundance of soil free-living nematodes was found to be 2-fold higher on the SFS than on the NFS. Thirty-nine genera, including 12 bacteria-feeders, 5 fungi-feeders, 12 plant-parasites, and 10 omnivore-predators, were found at the study site, with 34 genera on the NFS and 29 on the SFS. The generic diversity of the bacteriafeeding nematodes was higher on the SFS than on the NFS. This study elucidates the importance of slope orientation and its effect on the structural levels of soil microbial and nematode communities.     

Sequence polymorphism of candidate behavioural genes in Drosophila melanogaster flies from 'Evolution canyon'

This study focuses on the molecular features of three candidate behavioural genes in Drosophila melanogaster from the opposite slopes of Nahal Oren Canyon, Mount Carmel, Israel. These slopes display dramatic physical and biotic contrasts. Spatial variation of microclimatic conditions leads to adaptive differentiation and partial sexual isolation of populations, as suggested by our previous studies. The chosen candidate genes presumably contributing to genetic variation in sexual behaviour of Drosophila in the Canyon were desaturase, period, and no-on-transient A. These genes are known to include polymorphic repeated sequences, insertions/deletions, or nucleotide substitutions. The idea was that their polymorphism might be one of the determinants of behavioural peculiarities of flies derived from the opposite slopes. Indeed, interslope differences in the sequence encoding the (Thr-Gly)n repeat (exon 5) of the period gene were established, suggesting evolutionary functional importance. In particular, we unraveled variation in the length and composition of this region in different NFS (north-facing slope) and SFS (south-facing slope) lines. The 'European' allele (n = 20) was a 2.6-fold more abundant on the NFS compared to the SFS. This predominance probably gives some advantages for flies inhabiting wet and less warm conditions of the NFS. We suggest that repeat length/composition may influence the functional features of flies, i.e. habitat choice, nonrandom mating, and temperature adaptation. A series of female single-mate-choice tests show that females derived from NFS distinguish between males with specific per alleles (n = 17 vs. n = 20), as well as between males originated from the opposing slopes. Females from SFS were less discriminating and did not manifest significant deviation from random mating.     

Interspecific competition and torpor in golden spiny mice: two sides of the energy-acquisition coin

We studied the occurrence of torpor in golden spiny mice in a hot rocky desert near the Dead Sea. In this rodent assemblage, a congener, the nocturnal common spiny mouse, competitively excluded the golden spiny mouse from the nocturnal part of the diel cycle and forced it into diurnal activity; this temporal partitioning allows the two species to partition their prey populations, particularly in summer when the diet of the two species is comprised mainly of arthropods, and largely overlap. We studied the effect of the presence of the common spiny mice at two resource levels (natural food availability and food added ad libitum) on populations of golden spiny mice in four large outdoor enclosures: two with common spiny mice removed and two enclosures with populations of both species. We hypothesized that with interspecific competition and/or reduced resources, golden spiny mice will increase their use of torpor. As we expected, supplemented food reduced the total time spent torpid. In summer, when the different activity periods of the two species results in prey species partitioning, removal of the congener did not affect torpor in the golden spiny mouse. However, in winter, when insect populations are low and the two species of mice overlap in a largely vegetarian diet, removal of the common spiny mouse reduced torpor in golden spiny mice, whether food was supplemented or not. This result suggests that torpor, a mechanism that allows small mammals to sustain periods of low availability of resources or high energetic requirements, may also help them to tolerate periods of enhanced interspecific competition. This may be a significant short-term mechanism that reduces competition and hence increases fitness, in particular of individuals of the subordinate species whose accessibility to resources may be limited.     

Comparative non-shivering thermogenesis in adjacent populations of the common spiny mouse (Acomys cahirinus) from opposite slopes: the effects of increasing salinity

We compared non-shivering thermogenesis between two adjacent populations of the common spiny mouse Acomys cahirinus from different habitats, in relation to increasing salinity. Individuals were captured from the north- and south-facing slopes of the same valley, that represent "Mediterranean" and "desert" habitats, respectively. We hypothesized that the two populations of mice would differ in their thermoregulatory capacities, reflecting their need to cope with the environmental stress in each habitat. We measured resting metabolic rate by recording oxygen consumption, body temperature and response to an injection of exogenous noradrenaline. Mice were maintained on diets with increasing levels of salt intake to examine their abilities to cope with increasing osmotic stress. Mice from north-facing slopes generally had a higher resting metabolic rate and a higher increase in oxygen consumption in response to noradrenaline than mice from south-facing slopes. Increasing salinity decreased resting metabolic rate values, body temperature, and oxygen consumption in response to noradrenaline in both populations, and diminished slope-dependant differences. We suggest that these differences could be a result of an ongoing adaptive process to different climatic conditions, typical of the Mediterranean region, that are a demonstrable example of evolution in action.     

Genome Evolution of the Cyanobacterium Nostoc linckia under Sharp Microclimatic Divergence at "Evolution Canyon," Israel

We describe the genomic DNA diversity and divergence of the cyanobacterium Nostoc linckia from "Evolution Canyon," a microsite consisting of ecologically contrasting slopes, south-facing slope (SFS) and north-facing slope (NFS), at lower Nahal Oren, Mt. Carmel, Israel. The opposing slopes share their limestone lithology but vary greatly in their ecology, primarily because of different levels of solar radiation (which is six times higher on the SFS than on the NFS). The warm and xeric SFS displays a tropical African savanna, whereas the cool and mesic NFS displays a temperate South European Mediterranean live-oak maquis shrub forest. The cyanobacterium Nostoc linckia tested here is a sessile microorganism, growing as a carpet on rock surfaces and constantly exposed to environmental fluctuations of solar radiation, temperature, and desiccation. We demonstrate remarkable interslope and intraslope genetic divergence of the genome (including both coding and noncoding regions) of Nostoc linckia, by using 211 AFLP (amplified fragment length polymorphism) DNA molecular marker loci. Genetic polymorphism of N. linckia subpopulations on the ecologically harsher SFS was significantly (p <0.05) higher (p = 99.53%) than was that of the subpopulations on the climatically milder nfs (p = 85.78%). genetic polymorphism (p) and gene diversity (he) were significantly correlated with variables influencing aridity stress: solar radiation (sr) (rp = 0.956; p = 0.046), temperature (tm) (rp = 0.993; p = 0.0068), and day-night temperature difference (tdd) (rp = 0.975; p = 0.025). as in other tested organisms from "evolution canyon", but even more exceptionally because of its completely sedentary nature, we suggest that the climatically stressed sfs environment is responsible for this marked increase of genetic polymorphism, which is maintained by the combined evolutionary forces of diversifying and balancing selection. This could highlight the importance of ecological stress and selection in evolution and its remarkable effect on the genetic system across the prokaryotic genome.     

Microclimatic Divergence in a Mediterranean Canyon Affects Richness,Composition, and Body Size in Saproxylic Beetle Assemblages

Large valleys with opposing slopes may act as a model system with which the effects of strong climatic gradients on biodiversity can be evaluated. The advantage of such comparisons is that the impact of a change of climate can be studied on the same species pool without the need to consider regional differences. The aim of this study was to compare the assemblage of saproxylic beetles on such opposing slopes at Lower Nahal Oren, Mt. Carmel, Israel (also known as “Evolution Canyon”) with a 200–800% higher solar radiation on the south-facing (SFS) compared to the north-facing slope (NFS). We tested specific hypotheses of species richness patterns, assemblage structure, and body size resulting from interslope differences in microclimate. Fifteen flight-interception traps per slope were distributed over three elevation levels ranging from 50 to 100 m a.s.l. Richness of saproxylic beetles was on average 34% higher on the SFS compared with the NFS, with no detected influence of elevation levels. Both assemblage structure and average body size were determined by slope aspect, with more small-bodied beetles found on the SFS. Both the increase in species richness and the higher prevalence of small species on the SFS reflect ecological rules present on larger spatial grain (species-energy hypothesis and community body size shift hypothesis), and both can be explained by the metabolic theory of ecology. This is encouraging for the complementary use of micro- and macroclimatic gradients to study impacts of climate warming on biodiversity.     

黄喉貂日活动节律及食性的季节变化

2016年4月至2017年4月,采用红外相机技术和粪便分析法(频率法和剩余物干重法)对四川栗子坪国家级自然保护区内黄喉貂不同季节的日活动节律及食物组成变化进行了研究。结果显示:(1)黄喉貂主要在白天活动(昼间独立照片数占总独立照片数的85. 64%),不同季节黄喉貂日活动节律无显著差异(χ~2=126. 950,df=132,P=0. 608),但在不同季节其日活动高峰出现时间不同,春季的活动高峰在16:00~19:00(31. 65%),夏季活动高峰在15:00~18:00 (26. 32%),秋季活动高峰在13:00~16:00 (34. 31%),冬季活动高峰在11:00~14:00 (25. 00%),并且冬季夜间活动与其他季节相比明显增多;(2)黄喉貂取食食物有兽类、鸟类、昆虫类和植物类等,但兽类是黄喉貂最主要的食物来源,在一年中以兽类的出现频率最高,为95. 28%,兽类剩余物的总相对干重百分比达80. 99%,其次是植物、鸟类和昆虫;(3)黄喉貂对食物类别的利用表现出明显的季节差异,春、夏、秋三个季节黄喉貂粪便中兽类所占比重最多,春季鸟类出现频率较高,冬季黄喉貂粪便中植物所占比重明显增多。本研究表明,黄喉貂在不同季节其日活动节律和食性均表现出一定的差异,这可能与其繁殖特性和生理代谢需求有关。本研究揭示了黄喉貂的日活动节律及食性的季节性变化,充实了黄喉貂的生物、生态学资料,也为该物种的保护管理提供了参考资料。     

库木塔格沙漠地区野骆驼活动节律与家域特征

野生双峰驼(Camelus ferus)生存于中亚沙漠腹地, 是国家I级重点保护野生动物。为探究野骆驼活动节律和家域状况, 了解其时间和空间尺度上的活动模式, 为其有效保护管理提供支持。本研究于2012年5月至2013年7月利用GPS跟踪项圈先后对库木塔格沙漠地区7峰野骆驼进行轨迹跟踪。利用跟踪数据对野骆驼活动节律进行分析, 并采用布朗桥模型对野骆驼家域进行分析。结果表明: (1)野骆驼日活动节律呈现明显双峰模式, 属晨昏活动类型, 活动高峰期主要出现于上午6:00-9:00及下午15:00-20:00。(2)野骆驼晨昏活动高峰存在明显的季节性变动, 双峰从暖季到冷季向中午移动, 按间隔时间长短排序为: 夏季 > 春季 > 秋季 > 冬季。(3)野骆驼日活动强度有明显的季节性差异, 大小关系为: 夏季 > 秋季 > 春季和冬季, 春季和冬季间差异不显著。(4)野骆驼为核心家域利用类型, 且存在多个核心家域, 一些野骆驼家域分布于沙漠南北两侧, 意味着其具有横跨沙漠的运动能力。(5)野骆驼个体间家域面积差异显著, 性别间家域面积差异不显著。季节间家域面积差异显著, 从大到小排序为: 夏季(1,256.27 ± 427.45 km²) > 春季(556.90 ± 259.35 km²) > 秋季(396.77 ± 82.31 km²) > 冬季(250.83 ± 99.64 km²)。     

Exploring Phenotypic Plasticity in the LichenRamalina capitata: Morphology, Water Relations and Chlorophyll Content in North- and South-facing Populations

The present work analyses the morphology, anatomy, water relationsand chlorophyll content of thalli of the lichenRamalina capitatavar.protectafromtwo different populations exposed to contrasting microclimaticconditions due to differences in the orientation of the rocksurface. The population on the north-facing rock surface (NFS)was exposed to lower photosynthetic photon flux densities (PPFD),remained at high relative humidities for longer periods of timeand was exposed to lower temperatures than the population onthe south-facing surface (SFS). We proposed the hypothesis thatthe shadier the habitat the greater the ecological advantagefor enhanced light harvesting. Thalli from the SFS had shorterand wider lacinia, thicker thalli, mostly due to increased medullathickness, a higher water-retention capacity, a higher percentageof thallus volume occupied by the algal cells and a higher chlorophyllcontent than thalli from NFS. The phenotypic plastic responseof the traits studied inR. capitatavar.protectawas not directlyrelated to differences in the light availability, at least forthe range of PPFD experienced by the two populations studied,since the population exposed to higher PPFD exhibited largeramounts of light harvesting pigments. Both populations exhibitedthe same intrathalline distribution of algal cells and chlorophylls,which were more abundant in the apical than in the basal zonesof all thalli studied. Periods of water-induced metabolic activitywere shorter in the SFS than in the NFS, and structural andchlorophyll data indicated that thalli from the SFS were betterprepared for the photosynthetic exploitation of these brieferperiods and for maintaining thallus hydration into dry periods.These results suggest that differences in selective pressurebetween the two populations ofR. capitatavar.protectastudiedinvolved maximization of the photosynthetic exploitation ofthe periods of metabolic activity when they are brief, as hasbeen described for certain vascular plants from xeric environments. Ramalina capitatavar.protecta; algal cells; chlorophylls; water relations; microclimate; morphology; intrathalline variation; lichen; phenotypic plasticity     

在人工条件下光周期对大麝鼩(Crocidura lasiura)活动节律的影响

大麝鼩是一种夜行性动物,其夜间(19:00—6:00)的活动频次占全天活动总频次的88.67％;夜间活动呈双峰型曲线,前峰在19:00—24:00,后峰在2:00—5:00。其夜行性指数为6.31,但各季节不同:春季5.94,夏季4.01,秋季6.56,冬季8.71,比其他鼩鼱科动物高。每日活动总额次雄性高于雌性,雄性的夜行性指数亦比雌性高。在人工倒置光周期的条件下,其最初几天的活动节律极度紊乱,至第7天后才稳定地回到自然光周期的日活动次数水平。     

Adaptive differentiation of thermotolerance in Drosophila along a microclimatic gradient

We examined whether a remarkable occurrence - the physiological evolution of two Drosophila melanogaster populations, despite a spatial separation of only 100-400 m, was idiosyncratic and temporary, or persisted over multiple years. We ascertained the high-temperature tolerance of Drosophila descended from populations on the north-facing slope (NFS) and south-facing slope (SFS) of 'Evolution Canyon' (Lower Nahal Oren, Mt Carmel, Israel), which were collected in 1997, 1999, and 2000. Results for these Drosophila uniformly resembled other studies in many respects: an inverse relationship between survival and heat-shock temperature, male-female differences in thermotolerance, and inducible thermotolerance. Importantly, for all years of collection, SFS flies consistently exceeded NFS flies in basal and inducible thermotolerance after diverse heat shocks, with and without thermal pretreatment, and whether isofemale lines, synthetic populations, or inbred lines were compared. Inbred lines, however, had lower thermotolerance than outbred lines. Several nonexclusive processes may explain the evolution of such physiological differentiation.     

东海太平洋褶柔鱼生殖群体的空间分布及其与环境因子的关系

依据1997-2000年在东海(26°00′-33°00′N、120°30′-128°00′E)进行的4个季节的底拖网调查资料,分析了该海区太平洋褶柔鱼生殖群体的时空分布特征,同时结合广义相加模型(GAM),量化分析了各环境因子对于其种群成熟度指数(PMI)空间分布的影响机制。结果表明:太平洋褶柔鱼生殖群体春、夏、秋、冬4个季节在东海均有分布;秋季PMI值最高,春季最低;4个季节太平洋褶柔鱼生殖群体的分布范围均较广,主要集中在东海外海受台湾暖流和黑潮控制的水域。太平洋褶柔鱼生殖群体的环境适应性存在明显的季节差异:其分布的底温范围为:春季14.70-18.30℃、夏季13.18-20.91℃、秋季13.96-24.67℃、冬季14.33-19.75℃。底盐范围为:春季29.52-34.63、夏季31.57-34.27、秋季32.26-34.72、冬季34.25-34.70。水深范围为:春季55-179m,夏季43-176m、秋季40-184m、冬季79-152m。综上所述,东海太平洋褶柔鱼生殖群体的时空分布具有广范围、多季度的特点,这种分布特征可有效降低其幼体间的种间竞争,为确保其种群繁衍提供有利保障。     

Effects of environmental conditions on the movement patterns of Aedes aegypti (Diptera: Culicidae) into and out of experimental huts in Thailand

Mark‐release‐recapture experiments with Aedes aegypti were performed using experimental huts equipped with entrance and exit traps to evaluate their movement patterns during a two‐year period in Thailand. Results indicate no significant differences in the patterns of movement between the two years of observation. Movement into the huts occurred during the early morning period (06:00‐11:00) with a peak at 07:00 in the summer and rainy season and 09:00 in the winter. In contrast, the exit pattern was observed during the late morning (09:00‐12:00) and early afternoon (12:00‐16:00), with a peak at 16:00 in the winter, 11:00 in the summer, and 14:00 in the rainy season. Multiple regression analysis indicated that movements of Ae. aegypti females into and out of the huts were impacted by humidity and temperature during the day.     

Nematode Community Structure in Desert Soils: Nematode Recovery

The sugar-flotation-sieving (SFS) and Baermann-funnel (BF) methods were compared for nematode extraction efficiency. The SFS method recovered nematodes from more trophic groups whereas greater total numbers of individuals were recovered by BF. In a test to validate the efficiency of SFS, virtually 100% of the nematodes added to desert soil prior to extraction were recovered by four consecutive SFS washings of each soil sample. Estimations of nematode biomass in desert soils based on numbers of nematodes extracted by the two methods were similar unless there was large reserve of eggs in the soil. The biomass of nematodes from a Colorado desert soil was 0.9 g/m² as determined by both methods, whereas BF gave 0.17 g/m² for nematodes from a Mojave desert soil as compared to 0.9 g/m² with SFS.